1. FIELD OF THE INVENTION
This invention relates to a method of detecting a knocking within an internal combustion engine for varying the retard angle depending on the knocking intensity, and controlling the ignition timing of the engine.
2. DESCRIPTION OF THE PRIOR ART
In a conventionally known knocking detection method, as disclosed in U.S. Pat. No. 4,002,155, the output of a vibration detection apparatus is sampled within a constant period after ignition, low and high reference values are set from the average value, and the number of detection of vibration whose amplitude exceeds these reference values are counted thereby to discriminate the presence of knocking.
However, the prior art method in which only the number of vibration crossing the reference values are detected, has a drawback that the intensity of knocking can not be detected.